The field of the invention relates generally to circuit protection devices, and more specifically, to apparatus, systems, and methods for monitoring and operating a trip unit in a circuit protection device.
Circuit breakers are often used to protect, in a residential or commercial environment, against overcurrent conditions and/or ground fault conditions. In some circuit breakers, an electronic control system, referred to as a trip unit or an electronic trip unit, monitors one or more characteristics of electrical power to detect the presence of overcurrent conditions and causes an operating mechanism to separate circuit breaker contacts upon detection of an overcurrent condition by the trip unit. Separating the circuit breaker contacts, generally referred to as “tripping” the circuit breaker, interrupts the flow of current through the circuit breaker.
Some known systems include a watchdog circuit to monitor continued operation of the trip unit. The trip unit in such systems transmits a periodic signal, referred to as a watchdog signal, to indicate that it is still functioning. If the watchdog circuit does not receive the watchdog signal from the trip unit when expected, the watchdog circuit resets (i.e., turns off and restarts) the trip unit and/or trips the circuit breaker.